Abstract

Patients with congenital X-linked agammaglobulinemia (CAG)* have 1/2 to 1/3 the normal activity of ecto-5′-nucleotidase (ecto-5′-NT) in their peripheral blood mononuclear cells (1,2). Since peripheral B cells have at least 3 times more ecto-5′-NT activity than peripheral T cells (2,3) this deficiency can be largely explained by the absence of circulating B cells in these patients (4). In an attempt to develop a biochemical test for detection of carriers for CAG, ecto-5′-NT was measured in peripheral B cells and in lymphoblastoid (B) cell lines established from mothers and sisters of patients with CAG.